27/07/2023
Graphene, a material made of a single layer of carbon atoms, has been praised for its extraordinary properties, including being 200 times stronger than steel, lighter than paper, and possessing exceptional mechanical and electrical characteristics. However, recent research conducted by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory has shed light on its limitations.
The researchers focused on polycrystalline graphene, which is produced using chemical v***r deposition and contains nanoscale defects. They developed the first statistical theory for the material's toughness, which refers to its resistance to fracture. While polycrystalline graphene does exhibit high strength, it was found to have relatively low toughness—lower than diamond and slightly higher than pure graphite.
Berkeley Lab scientist Robert Ritchie, an expert in material failure, highlighted the importance of toughness in structural materials. While high strength is impressive, it needs to be complemented by resistance to fracture to be practically useful. The study's authors created a mathematical model that considers the nanostructure of the material to better understand and predict its failure behavior.
In engineering, materials used in critical structures, such as nuclear reactor pressure vessels, need to possess both strength and toughness. Strength refers to a material's resistance to deformation, whereas toughness addresses its ability to withstand cracks and fractures. While strong materials like ultra-high-strength steels are suitable for specific purposes, they are not used in critical structures due to the risk of catastrophic failure. Instead, tough materials are preferred to ensure the overall safety and reliability of such structures.
